


Good Dog

by corruptfiction



Category: Voltron: Legendary Defender
Genre: 8 year old Keith, Anal Fingering, Anal Sex, Ass to Mouth, Bestiality, Blowjobs, Dog Dick, Galra Keith (Voltron), Galra heat starts young, Like, M/M, Mating Cycles/In Heat, Oral Sex, Other, Rimming, Shiro fucks Kosmo, really young
Language: English
Status: Completed
Published: 2019-01-02
Updated: 2019-01-03
Packaged: 2019-10-02 12:11:02
Rating: Explicit
Warnings: Underage
Chapters: 2
Words: 1,350
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/17263976
Author URL: https://archiveofourown.org/users/corruptfiction/pseuds/corruptfiction
Summary: Crappy title for crappy writingGalra heat starts at an early age, and Keith goes into his first heat at age 8. Kosmo helps him through it.





	1. Chapter 1

Keith writhed in his bed, the Galra heat causing him to ache with need. It hit him earlier than a puberty would, but even if it hadn’t, it wasn’t the same as a human puberty. He let out a quiet whine, trying not to disturb the otherwise silent house. His older brother Shiro was asleep in the room across the hall.

He didn’t understand what was happening to his body, or  _ what _ exactly his body was aching for, but it was overwhelming his senses. The way his cock hardened and his hole leaked some slippery fluid scared him. It had already soaked through the sheets, what if it didn’t stop? What if he had to tell Shiro and go to a doctor? He didn’t want to go through that embarrassment.

He tugged down his pajama pants with spaceships on them and kicked them off of the bed, Cautiously, he touched his penis and moaned out, quickly stifling it with his hand. Kosmo lifted his head and his ears perked up from where he lay at the bottom of the bed. The dog they had rescued had quickly become attached to the young Keith, and Keith loved him just as well.

Kosmo padded his way up to Keith and nudged his cheek with his muzzle.

“N-not now, Kosmo..” Another whine forced its way out of Keith’s throat as he

spoke and the dog let out a similar one back, worried for his owner. He squirmed between Keith’s legs and looked up at him before his tongue lapped at the leaking cock, licking up the precum oozing from the slit. His large tongue laved from Keith’s hole all of the way to the head of his cock repeatedly, taking in all of the liquid from him. The tongue dipped just barely into Keith’s twitching entrance and he came from the sensations, Kosmo’s rough tongue against the head immediately lapping it all up.

Kosmo continued to lick him, his tongue delving deeper into Keith’s hole as he heard the whines get louder when he licked there. The eight year old arched his hips up off of the bed as the long dog tongue reached his sweet spot, “P-please!”

Keith flipped himself over to allow a better angle for the tongue to plunge into him, but then Kosmo stood and his front paws came down over Keith’s sides, furry chest against the boy’s back.

It took a few thrusts to line his thick, burning hot cock up with the virgin hole, but the heat’s natural lubrication and stretching allowed the dog to slide all of the way into him in one go when the tip finally caught. Keith winced at the sting but soon he adjusted to the foreign feeling and pushed back to meet Kosmo’s thrusts.

“Y-yes, good boy, good boy Kosmo!”

The dog seemed spurred on by the praise, thrusts gaining speed as his knot began to swell. Keith heard the door creak open but couldn’t bring himself to care as the knot stretched his hole ever wider and he came hard against the sheets, one hand going back to hold Kosmo against him as he let out a pleasured hiss of, “yesss..”

Shiro stared at his baby brother, with their dog balls deep in him, and snapped a photo on his phone.


	2. More

**Summary for the Chapter:**

> This was gonna be a oneshot until I decided to write more filthy sin and its gross so here take it

Keith couldn’t breathe.

He started to squirm as Shiro sitting on his face cut off his air supply, but despite the pain as he tried to inhale, his tiny cock only wept more precum. Kosmo’s tongue was deep inside of his hole, eating his own cum out of it, rubbing against the special spot inside of him, and Keith’s own tongue was sliding in and out of Shiro’s entrance as best as he could, but he was young. His tongue couldn’t reach that far, so Shiro had to get lower and lower until he was actually sitting atop Keith’s mouth.

Shiro lifted his hips to allow his younger brother to take a  mouthful of air before lowering himself on the child’s tongue again, letting out quiet gasps at the feeling. The heat kept Keith horny, even right after being fucked into the mattress by Kosmo, and Shiro took advantage of it by shoving his cock into Keith’s mouth while the boy was still knotted on the dog’s dick. Soon he had turned around and ground his ass into Keith’s face until the boy got the message and started licking him.

“Maybe you should blow Kosmo next, after all he’s doing for you. He’s already made himself alpha over you so you’ll have to submit to him. Maybe I should assert myself over him..”

Shiro absently spoke while riding Keith’s tongue until the boy squirmed again and he had to pull off so Keith could breathe once more.

“Come here, boy,” Shiro patted his legs for Kosmo to come and the dog was happy to stand over Keith’s body, in front of Shiro who straddled Keith’s face. The older backed up out of the way and guided the dog forward until his heavy cock pressed against Keith’s lips. Instinctively the boy opened and suckled on the pointed tip. “Good job, Keith, just like that,” Shiro murmured as he rounded to be behind the dog, his knees now on either side of Keith’s torso. 

Shiro scooped up some of the slick leaking rapidly from Keith’s used hole and spread it over his fingers before carefully pressing one into Kosmo’s virgin ass. The dog’s ears perked up and his hind legs shook as he thrust into Keith’s mouth, but he didn’t move away as Shiro started to finger him open, soon adding another slicked up finger and scissoring. Soon the dog was whimpering and pulled back so his cock fell out of the boy’s mouth. Shiro chuckled, the dog was drawing out his own orgasm.  

With only two fingers in him, Kosmo already seemed desperate to be fucked, lowering his head and raising his ass toward Shiro, who smirked at the submissive gesture. “That’s right, good boy, I’m going to fuck you while you fuck Keith’s mouth.” The dog wagged his tail at the words ‘good boy’ and Shiro laughed. He lifted Kosmo’s tail out of the way as he pressed his cock inside of the tight channel, and Kosmo howled as he was stretched open and at that moment Keith leaned his head forward to suck on his thick dog cock again.

Shiro didn’t wait long to start thrusting, and each thrust pushed Kosmo’s dick further down Keith’s waiting throat. It was bliss, the tight heat pulling him in each time he had to pull outward. He idly wondered if he could convince Keith to eat his come out of the dog’s hole afterward but he doubted that would happen.

He could feel his balls slapping against the dog’s own with each thrust and eventually felt the knot at the base of Kosmo’s cock swell when his balls slapped against it too. Despite continuing to fuck into the animal he peered under to see the giant knot pop into Keith’s mouth, and suddenly Kosmo couldn’t pull it out again, the opening too small. Shiro grunted in arousal and watched as Keith’s mouth was filled to the brim with the dog’s cum, cheeks inflated and a bit dribbling out the corners of his mouth and even a little out of his nose. Kosmo continued to pump his load into the child’s throat and the audible gulping as Keith tried to swallow the influx of liquid brought Shiro to the edge. He held Kosmo’s furry hips as his thrusts stuttered while he released into the waiting hole, filling the pet with his semen and fucking him through it before pulling out and laying beside his baby brother.

Keith’s jaw ached, still held open as he waited for Kosmo’s knot to deflate and tongued the slit absentmindedly, eyes rolled back into his head. He looked fucked out and Shiro noticed the mess of the young boy’s cum all over his own stomach.

“Next time,” Shiro promised while petting Keith’s hair, “I’ll have your ass.”


End file.
